DE 20 2008 006 834 U1 has already disclosed a filter element which comprises a frame and bag-like filter pockets connected thereto, wherein the filter pockets, on the inflow side, have openings so that a fluid which is to be filtered can enter into the interior spaces of the filter pockets, and wherein the interior spaces taper in the direction of an outflow side.
Filter elements of this kind are used as so-called pocket filters in industrial air filtration. This use is mentioned merely by way of example.
The air which is to be filtered enters into the bag-like filter pockets via the openings and exits out of the filter pockets again on the outflow side, on a side which is directed away from the openings. The air here flows through the walls of the filter pockets, which are produced usually from nonwoven fabrics. Nonwoven fabrics are mentioned here merely by way of example. In addition to nonwoven fabrics, it is also conceivable to use other materials which hold back gas or particles.
The air is filtered as it flows through the walls. The filter pockets are of essentially V-shaped design and have their pointed ends projecting from a frame ring.
A flow field forms in the region of the pointed ends or edges, said flow field being determined essentially by the speed at which the air enters into the filter pockets and/or exits from the same.
Vortices can disadvantageously form in this flow field. These vortices result in an undesired loss in pressure at the filter element. Loss in pressure is understood to be the difference between the static pressure on the inflow side, that is to say upstream of the openings, and the static pressure on the outflow side. This loss in pressure may be up to 50%. The loss in pressure according to this description is measured in accordance with DIN EN 779.
High frictional losses may occur in the flow field as a result of the vortices. Said frictional losses result in a loss in energy and thus in a loss in pressure.